FIG. 6 is a cross-sectional view of a conventional electro-acoustic converter used as a loud speaker or a receiver incorporated in an electronic device such as a mobile telephone. Magnet 1 is sandwiched between upper plate 2 and yoke 3 to configure magnetic circuit 4 of an inner-magnet type. Yoke 3 is press-fitted into frame 6 made of a resin material and bonded with adhesive. Diaphragm 7 is fixed to a circumferential edge of frame 6. Voice coil 8 for vibrating diaphragm 7 is attached to diaphragm 7 in a manner that it is located in magnetic gap 5 of magnetic circuit 4.
A lead wire of voice coil 8 is connected to one end of terminal 10 by soldering. Frame 6 retains a part of terminal 10 in its molded structure. Terminal 10 is bent over at bent portion 10A so as not to protrude outward from a boundary of an outer dimension of frame 6. Terminal 10 is formed by a process of bending a piece of sheet metal, and movable end 10B is used to make contact with an power supply section of a system by taking advantage of a spring tension of the sheet metal. Frame 6 is provided with stopper 9 protruding from the lower end thereof, which is formed unitary with frame 6 during a process of injection-molding the resin material.
Stopper 9 restricts a bending range of terminal 10 so as to prevent it from being bent beyond a threshold value of reversibility of a material of the sheet metal constituting terminal 10. This prevents terminal 10 from being bent to any such degree that exceeds the threshold value of reversibility even when loud speaker 11 is forcibly pressed while being mounted to an apparatus. It thus clears such drawbacks as terminal 10 getting damaged when loud speaker 11 is mounted to an apparatus, and terminal 10 becoming unstable to maintain contact with the apparatus due to a deficiency of spring tension of terminal 10. Loud speaker 11 illustrated above is disclosed in, for example, Japanese Patent Unexamined Publication, No. 2003-37890.
When an apparatus incorporating loud speaker 11 is accidentally dropped, however, there may be a possibility that stopper 9 becomes broken due to an excessive force of impact. If stopper 9 is broken in this way, it may cause metal terminal 10 to exceed the threshold value of reversibility of the spring tension, thereby resulting in an unstable contact with the power supply section of the apparatus. As a consequence, there can be a failure of contact, which interrupts signals whenever the apparatus is subjected to an impact or a vibration.